(a) Technical Field of the Invention
The present invention relates to an improvement in the positioning structure of a single-pull reel, and in particular to a positioning structure which is durable in use, easy to operate and accurate in positioning and reduces noise in operation.
(b) Description of the Prior Art
Conventional type of positioning a cord within a reel is the application of a steel bead. As shown in FIGS. 6 and 7, the reel A10 comprises a front cover A1, a spiral spring A2, a sliding seat A3, a transmission cord A4, a positioning steel bead A5 and a rear cover A6. In this conventional structure, the sliding seat A3 contains the spiral spring to restore the transmission cord A4 to its original position. The steel bead A5 slides within the sliding seat A3 so as to position the cord A4. The bottom section of the sliding seat A3 has a passage A31 so that the steel bead A5 could roll, engage and disengage within the passage A31. Thus when the sliding seat A3 is pulled at a high speed and high speed retraction, the steel bead passage A31 will also in operation. Under this condition, the steel bead passage A31 under a high speed rotation, does not comply the requirements of stable engaging and sliding, thus extreme gap and error are formed. Relatively, design on rail is difficult and high precision is needed. Thus the cost of producing the rail is high. In addition, when there is a friction and the error on the gap is too large, the dislocation of the steel bead A5 is expected and thus, the function of positioning is lost. As a result, frequent dislocation of cord in the reel occurs and the longevity is lost.